Apparatus for vibratory finishing

ABSTRACT

In a vibratory finishing machine of the type in which an annular tub is vibrated by a motor having a shaft with eccentric weights, reversal of the direction of movement of finishing media around the tub is effected by reversing the relative angular position of the weights, this weight reversal being effected automatically in response to reduction of the motor speed, without the usual requirement of reversing the direction of rotation of the motor. Weights reversal is preferably effected by centrifugal force against the action of a toggle spring device.

Sates Patent [191 Barlett et al.

APPARATUS FOR VIBRATORY FINISHING Inventors: William John Barlett,Hempstead; Frederick George Boniface, Hemel Hempstead, both of EnglandRoto-Finish Limited, Hertfordshire, England Filed: Nov. 28, 1973 Appl.No.: 419,660

Assignee:

US. Cl. 51/163, 259/72 Int. Cl. B24b 31/06 Field of Search 259/72;241/175; 51/163 References Cited UNITED STATES PATENTS 9/1971 Balz5l/163 Oct. 29, 1974 3,811,231 5/1974 Kobayashi 51/163 PrimaryExaminerHarold D. Whitehead Attorney, Agent, or Firm-Brisebois & Kruger[57] ABSTRACT In a vibratory finishing machine of the type in which anannular tub is vibrated by a motor having a shaft with eccentricweights, reversal of the direction of movement of finishing media aroundthe tub is effected by reversing the relative angular position of theweights, this weight reversal being effected automatically in responseto reduction of the motor speed, without the usual requirement ofreversing the direction of rotation of the motor. Weights reversal ispreferably effected by centrifugal force against the action of a togglespring device.

5 Claims, 7 Drawing Figures APPARATUS FOR VIBRATORY FINISHING A knownform of apparatus for effecting the vibra-.

tory finishing of parts comprises a chamber which is annular in planform anda rotary shaft disposed vertically on the axis of the chamberand carrying in axially spaced relation a pair of eccentric weights, oneof which leads the other by agiven angle, the chamber and the shaftbeing supported by spring means which parts are" introduced.

A variety of expedients have already been used andproposed.forseparatingthe parts from the mixture when thefinishingoperation is'complete, the motion of the mixture resulting fromcontinued operation of the apparatus being used to deliver the mixtureon to a separating screenwhich retains the finished parts and-allowsthefinishing medium to pass through and return (usually directly) to thechamber.

In particulanit has been proposed to effect such separation by reversingthe direction of rotation of the shaft and arranging that this reversalshall cause an alteration in the relative angular positions of theweights so that the same weight still leads the other; the directionin'which the mixture travels round the annular chamber-is thus reversedand means such as a hinged flap then operate to direct the mixture ontoa separating screen of the above character, the said means beinginoperative while the mixture is travelling in the normal direction.

We have found that the direction in which the mixture travels aroundthe. annular chamber can be reversed (allowing separation to be effectedas explained above) without the necessity for reversing the direction ofrotation of the shaft (thus making it unnecessary to provide reversinggear, or a reversible driving motor) by'appropriately altering therelative positions of the two weights.

The invention accordingly includes a method of operating a vibratoryfinishing machine of the type described, wherein the shaft is firstdriven in one direction with one weight leading the other, the relativeangular position of the weights in then altered so that (for the samedirection of rotation) the second mentioned weight leads the first, andthe shaft is rotated in the same direction as before, whereby to impartto the mixture a reversed circulatory movement which facilitatesdelivery of the mixture on to a separating screen.

While it would be possible to effect the required alteration in therelative position of the weights by direct manual adjustment, this willnot in general be very convenient.

The invention further provides a vibratory finishing machine of the typedescribed, including means for reversing the relative angular positionof the said weights in response to interruption of rotation'of theshaft.

To effect finishing treatment, the shaft is rotated in a direction whichwill cause the mixture to travel round another detail in three differentbottom weights 13 posite direction around the tub and thus to bedelivered on to the separating screen.

The invention and presently preferred ways of carrying it into practiceare further described below with reference to the drawings accompanyingthe provisional specification in which:

FIG. 1 is a side elevation chine;

FIG. 2 is a plan view thereof;

FIGS. 3 and 4 are side views of a detail in two different conditions ofoperation;

FIGS. 5, 6 and 7 are diagrammatic side elevations of conditions ,ofoperation.

a bowl tub 10 shaped to provide a treating chamber 11 which is annularin plan view and has in cross section the form of an open-topped channelwith vertical side walls and a semi-circular base. On the vertical axisof the bowl there is mounted a shaft driven by an electric motor 12 andcarrying eccentrically disposed top and and 14. The bowl, shaft andmotor are supported by springs 15 from a base 16. During the finishingtreatment, the material in the treating chamher is caused to travelclockwise around the chamber, as viewed from above. The chamber 11,instead of being completely circular, includes a short straight section17 accommodating a flap 18, one end of which is hingedly supported bythe tub 10 or the screen 19 at'a level above the topof the materialinthe. channel. As indicated in FIG. 1,1this flap can swing between asubstantially horizontal position and a position inclined at some 45 tothe'horizontal with the free end of the flap resting'on the bottom ofthe chamber 11. The free end of the flap is shaped to fit the bottom ofthe chamber and the flap extends across the full width of the chamher,so that when lowered the flap forms a substantially complete barrieracross the chamber. Adjacent the upper, hinged end of the flap there ismounted on the tub 10 a separating screen 19 which extends horizontallyabove the chamber 10 and projects beyond it.

While the finishing operation is being performed, the flap l8 rests onthe top of the material 20 circulating in the chamber, as shown in FIG.4, and allows the op-' eration to proceed normally. When the finishingoperation is complete and it is desired to discharge the finished parts,the material in the chamber is caused to circulate in acounter-clockwise direction. The action of the material 20 on the flapl8 forces the latter down into its inclined position, as shown in FIG.3, so that the material travels up the ramp constituted by the flap andon to the separating screen 19. The finishing medium passes through thescreen and drops back into the chamber 11, while the finished parts areretained on the screen and discharged over its outer projecting end.

The required reversal of the direction of circulation of the material inthe chamber is obtained by giving one of the weights (say the top weight13) the construction shown somewhat diagrammatically in FIGS. 5 to 7.The shaft 21 of motor 12 carries a transverse pivot 22 which supportsfor rocking movement an arm 23. Secured to of a vibratory finishing ma-The machine illustrated in FIGS. 1 and 2 comprises the lower end of arm23 is a closed container 24, which is rectangular in plan view and ispartly filled by a freely movable mass, such as a plurality of steelballs 25. A compression spring toggle 26, engaged between abutments onarm 23 and shaft 21, operates (when shaft 21 is stationary) to hold thecontainer 24 tilted into one or other of the two extreme positions shownin FIGS. and 7.

Assuming that the parts are initially in the position shown in FIG. 5,the balls 25 having rolled by gravity to the lower end of the container,rotation of shaft 21 gives rise to a centrifugal force acting on theballs 25 which causes container 24 and arm 23 to turn (clockwise in thefigure) about pivot 22 into the position shown in FIG. 6. During thefirst part of this movement spring 26 is compressed, but having beenmoved over centre its expansive force assists in holding the parts inthe position shown in FIG. 6. When the rotation of shaft 21 is stopped(or very greatly slowed down) so that centrifugal force ceases to act onthe balls 25, spring 26 maintains the container in the position intowhich it has been tilted and the balls roll down by gravity into theopposite end of the container as indicated in FIG. 7. When next theshaft 21 is set into rotation, the movements are repeated in reverse.

Thus during rotation of shaft 21 the balls 25 occupy one or other of twopositions lying on opposite sides of shaft 21 and they move from oneposition to the other automatically each time that the shaft is broughtto a standstill. By disposing the other eccentric weight on the shaft inan angular position which is intermediate the two alternative positionsof the balls 25, the required alteration in the relative positions ofthe two weights is thus obtained automatically.

It will be appreciated that the method of achieving weight reversal doesnot depend on the shaft being stopped completely, but that this willoccur when the speed of rotation is sufficiently reduced to allow themass to move to the opposite end of the container. It should also beunderstood that the shaft does not have to be seen in the same directionas before weight reversal, the latter being responsible for reversal ofthe circulatory motion of the mixture, irrespective of the direction ofrotation of the shaft. However, the advantages of being able to run theshaft always in the same direction make it highly desirable to do sowhen possible.

We claim:

1. A vibratory finishing machine comprising an annular treatment chamberfor a finishing medium and workpieces non rotatably mounted on a springsuspension; a motor securely mounted to said chamber and having a motorshaft disposed vertically on the axis of said chamber; first and secondeccentric weights mounted on said shaft in axially spaced relation andangularly spaced relation to each other; and means responsive tointerruption of rotation of said motor shaft to effect reversal of therelative angular position of said weights.

2. A machine according to claim 1, wherein one of said weights isconstituted by means operable to move the effective mass of said weightbetween alternate positions, lying on angularly opposite sides of thesecond weight, these means being operable automatically each timerotation of said shaft is interrupted.

3. A machine according to claim I, wherein one said weight comprises acontainer, a loose mass partially filling said container, meanspivotally supporting said container on said motor shaft for rockingmovement about a transverse axis, the loose mass being adapted to occupythat end of said container which is lowermost with said shaft at rest atany time and said container being tilted about said transverse axis tocause the other end thereof to be lowermost when said shaft is rotatingat its operating speed, by centrifugal forces acting on said mass.

4. A machine according to claim 3, further comprising toggle actingspring means acting between said shaft and said container and tending tohold the latter in the pivotal position to which it was last moved bythe effect of centrifugal forces acting on said mass.

5. A machine according to claim 1 further comprising a pivoted flapmounted in the chamber, which flap is adapted to deflect freely topermit circulatory movement of the mixture in one direction around saidchamber and which, upon reversal of the circulatory movement, is adaptedto assume a position in which it deflects the mixture on to a separatingscreen which effects separation of the parts from the finishing medium.k

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3.8".071Dated October 29. 197

Inventor) WILLIAM JOHN BARTLETT and FREDERICK GEORGE BONIFACE It viscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

[75] Inventors: William John Bart lett Hemel Hempstead;

Frederick George Boniface, Hemel Hempstead, both of England .fji necarc: sealer? this 22115 c'ay of April 1.1775.

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1. A vibratory finishing machine comprising an annular treatment chamberfor a finishing medium and workpieces non rotatably mounted on a springsuspension; a motor securely mounted to said chamber and having a motorshaft disposed vertically on the axis of said chamber; first and secondeccentric weights mounted on said shaft in axially spaced relation andangularly spaced relation to each other; and means responsive tointerruption of rotation of said motor shaft to effect reversal of therelative angular position of said weights.
 2. A machine according toclaim 1, wherein one of said weights is constituted by means operable tomove the effective mass of said weight between alternate positions,lying on angularly opposite sides of the second weight, these meansbeing operable automatically each time rotation of said shaft isinterrupted.
 3. A machine according to claim 1, wherein one said weightcomprises a container, a loose mass partially filling said container,means pivotally supporting said container on said motor shaft forrocking movement about a transverse axis, the loose mass being adaptedto occupy that end of said container which is lowermost with said shaftat rest at any time and said container being tilted about saidtransverse axis to cause the other end thereof to be lowermost when saidshaft is rotating at its operating speed, by centrifugal forces actingon said mass.
 4. A machine according to claim 3, further comprisingtoggle acting spring means acting between said shaft and said containerand tending to hold the latter in the pivotal position to which it waslast moved by the effect of centrifugal forces acting on said mass.
 5. Amachine according to claim 1 further Comprising a pivoted flap mountedin the chamber, which flap is adapted to deflect freely to permitcirculatory movement of the mixture in one direction around said chamberand which, upon reversal of the circulatory movement, is adapted toassume a position in which it deflects the mixture on to a separatingscreen which effects separation of the parts from the finishing medium.